Experimental research on reduction of agricultural non-point source pollution using pond wetland

In order to study the removal effect and laws of nitrogen and phosphorus pollutants drainaged form farmland by pond wetland, a typical pond was selected and transformed in Zhanghe irrigation district, Hubei province. Water samples of nitrogen and phosphorus form the pond were collected for analysis during the whole growing season of rice from May to September in 2009. The results showed that the average removal rate of total nitrogen, total phosphorus with typical pond wetland were 45.88% and 44.20% respectively, high efficiency in pollutant removal was obtained. Comparative experiment of three processing units showed that the units which optimized plant density, the ability of removing nitrogen increased significantly, wetland plants absorbed nitrogen was the important way to remove nitrogen. Compared with unit Ⅱ(sediment of wetland was dregdged ,it was backfilled with new sediment and planting density was readjusted), the effect of removing phosphorus by unit Ⅲ(planting density in wetland was optimized) was better, phosphorus was adsorbed by sediment play an important role in removing phosphorus in wetland, which provided valuable reference for the study of wetland in future.